1. Field of the Invention
The present invention relates to a fuel cell. More particularly, the present invention relates to a fuel cell structure used when a solid oxide type fuel cell element is arranged in a flame or in a portion close to the flame.
2. Description of the Related Art
Conventionally, there is proposed a fuel cell in which a solid oxide type fuel cell element is arranged in a flame or in a portion close to the flame and the temperature of the solid oxide type fuel cell element is maintained at its operation temperature by the heat of the flame so as to generate electricity. For example, this solid oxide type fuel cell is disclosed in the official gazette of JP-A-6-196176 (item [0019], FIG. 5).
The official gazette of JP-A-6-196176 discloses a solid oxide type fuel cell including: a tube body made of zirconia solid electrolyte; a fuel electrode arranged outside the tube body; and an air electrode arranged inside the tube body, wherein the solid oxide type fuel cell is arranged so that the fuel electrode is exposed to a reducing flame portion of the flame. This fuel cell generates electricity in such a manner that radicals and others existing in the reducing flame are utilized as fuel and air is supplied into the tube by means of convection or diffusion.
In this type fuel cell, the flame is directly used. Therefore, the electro-motive time can be reduced. Further, the structure of the fuel cell is so simple that the size and weight can be reduced, by which the manufacturing cost can be advantageously lowered. Furthermore, it is possible to utilize a combustion device, an incinerator and the like as an electric power supply device. Therefore, the utility value of this type fuel cell is high.
However, since the solid oxide type fuel cell element is directly heated by a flame, cracks tend to be caused by a sudden temperature change. The solid oxide type fuel cell element, in which cracks are caused, breaks up afterward. Therefore, it becomes impossible to generate electricity.